1. Chapter 12: The Solar System
Section 3: The Outer Planets

2. A. Jupiter – fifth planet from the Sun, largest planet in the solar system

3. 1. Atmosphere – primarily hydrogen and helium
a. Below the atmosphere, liquid hydrogen and helium are suspected

4. b. Solid rocky core may exist below liquid level

5. c. The Great Red Spot is the most spectacular of Jupiter’s many constant high-pressure gas storms

7. 2. Has at least 61 moons, four are relatively large and have atmospheres

8. a. Io – is very volcanically active;
the closest
large moon
to Jupiter

9. b. Europa – composed mainly of rock;
may have an
ocean of
water under
a thick layer
of ice

10. c. Ganymede – largest moon in solar system;
even larger
than planet
Mercury

11. d. Callisto – cratered rock and ice crust
may surround
a salty ocean
and rock core

12. B. Saturn – sixth planet from the Sun, second largest in the solar system, lowest density

13. 1. Thick outer atmosphere of hydrogen, helium, ammonia, methane, and water vapor
2. Might have a small rocky core

14. 3. Each large ring composed of thousands of ringlets of ice and rock particles

15. 4. Has at least moons
a. Largest moon, Titan, is larger than the planet Mercury
b. Thick clouds on Titan prevent scientists from seeing surface

16. C. Uranus – seventh planet from the Sun, large and gaseous

17. 1. Has thin, dark rings
2. Atmosphere
of hydrogen, helium, and methane

18. 3. Methane makes the planet bluish-green in color
4. Axis of rotation nearly parallel to plane of orbit

19. D. Neptune – usually the eighth planet from the Sun, large and gaseous

20. 1. Bluish-green colored atmosphere similar to that of Uranus
2. Storms on
Neptune reveal an active and rapidly changing atmosphere
“Small dark spot”, photographed by Voyager 2 in October, It has since vanished.

21. 3. Has at least 11 moons, of which pinkish Triton is the largest

22. E. Pluto – dwarf planet, occasionally closer to the Sun than Neptune, one of the three dwarf planets

23. 1. Has a thin atmosphere and a solid, rocky surface
2. Has three
moons
Now known to have 5 moons

24. 3. The IAU defined the terms planet and dwarf planet in 2006.